Installation for the generation of energy

ABSTRACT

An installation for generating energy comprises a compressor assembly for compressing air, having a low-pressure compressor, which is connected to a high-pressure compressor via a primary air path. Furthermore, a compressor turbine assembly is provided for the purpose of driving the low-pressure compressor and/or the high-pressure compressor. The installation also has a combustion device for burning a suitable mixture of compressed air and a fuel, and a power turbine with a rotatable shaft for releasing mechanical energy. An exhaust-gas pipe system is connected to the exhaust-gas outlet of the power turbine. The installation comprises a secondary air path which, at an inlet end thereof, is connected between the outlet of the low-pressure compressor and the inlet of the high-pressure compressor, in such a manner that, of the compressed air originating from the outlet of the low-pressure compressor, a primary airflow passes via the primary air path to the high-pressure compressor and a secondary airflow passes into the secondary air path. At the secondary air path, first water injection means are provided for injecting water into the secondary airflow. The secondary air path is connected, at an outlet end thereof, to the connection between the outlet of the compressor turbine assembly and the inlet of the power turbine.

CROSS REFERENCE TO RELATED APPLICATION

This application claims priority to International Application No.PCT/NLO2/00001 filed Jan. 2, 2002, claiming priority of Netherlandsapplication No. 1017029 filed Jan. 4, 2001.

FIELD OF THE INVENTION

The present invention relates to an installation for generating energy.

BACKGROUND OF THE INVENTION

U.S. Pat. No. 5,669,217 and EP 1 039 115 each disclose an installationfor generating energy having a compressor assembly for compressing air.The compressor assembly comprises:

a low-pressure compressor having an air inlet and an outlet,

a high-pressure compressor having an inlet and an outlet, the outlet ofthe low-pressure compressor being connected to the inlet of thehigh-pressure compressor via a primary air path,

a compressor turbine assembly for driving the low-pressure compressorand/or the high-pressure compressor, which compressor turbine assemblycomprises a single compressor turbine or a plurality of compressorturbines arranged in series, and which compressor turbine assembly hasan inlet and an outlet, the inlet being connected to the outlet of thehigh-pressure compressor.

The known installations further comprise cooling means for cooling theair at a location which lies upstream of the outlet of the high-pressurecompressor and a combustion device for burning a suitable mixture ofcompressed air and a fuel.

The known installations further comprise a power turbine with arotatable shaft for delivering mechanical energy, which power turbinehas an inlet, which is connected to the outlet of the compressor turbineassembly, and an exhaust-gas outlet. Also provided is an exhaust-gaspipe system, an inlet end of which is connected to the exhaust-gasoutlet of the power turbine.

In these known installations, the cooling means for cooling the airbetween the low-pressure compressor and the high-pressure compressor aredesigned as water injection means.

As is known from the prior art, there are various reasons for usingwater injection in an installation of this type. One important reason isthat the water injection creates the possibility of achieving a higherefficiency of the installation. Another reason is the possibility ofreducing the polluting emissions from the installation.

It should be noted that the term “water injection” in the context of thepresent invention incorporates any form of injection of water, i.e.including the atomisation of water, the injection of preheated water orof steam, etc.

With the installations, which have become known to date, theadvantageous effects referred to above cannot be achieved to asatisfactory extent.

OBJECTS OF THE INVENTION

A first object of the present invention is to propose measures, whichlead to an improved installation.

In particular, it is an object of the invention to provide aninstallation with a higher efficiency than the known installations ofthe type described in the preamble.

Another object of the invention is to propose measures through whichoptimum use is made, for the heating/evaporation of the injected water,of the heat in the exhaust gases from the installation.

Yet another object is to provide an installation with lower pollutingemissions than the known installations of the type described in thepreamble.

Yet another object is to provide an installation in which optimumoperating conditions are created for one or more of the components ofthe installation, which is advantageous, for example, for the technicalimplementation of the relevant component(s).

SUMMARY OF THE INVENTION

The present invention provides an installation for generating energy,which is characterized in that a secondary air path is provided, which,at an inlet end thereof, is connected between the outlet of thelow-pressure compressor and the inlet of the high-pressure compressor,in such a manner that, of the compressed air originating from the outletof the low-pressure compressor, a primary airflow passes to thehigh-pressure compressor and a secondary airflow passes into thesecondary air path, and in that at the secondary air path there arefirst water injection means for injecting water into the secondaryairflow, and in that the secondary air path, at an outlet end thereof,is connected to the connection between the outlet of the compressorturbine assembly and the inlet of the power turbine.

Dividing the airflow originating from the low-pressure compressor into aprimary airflow and a secondary airflow allows optimum operatingconditions to be achieved for the high-pressure compressor, while it isalso possible for effective injection of water into the secondaryairflow to take place. In this case, the cooling means which cool theprimary airflow may likewise be designed as water injection means which,however, are independent of the water injection means for the secondaryairflow.

Preferably, the primary airflow is greater than the secondary airflow;by way of example, the primary airflow is 70-90% and the secondaryairflow 10-30% of the total airflow delivered by the low-pressurecompressor.

The secondary airflow is combined with the primary airflow downstream ofthe compressor turbine assembly, so that this secondary airflow can bekept at a relatively low pressure. If the pressure at the point wherethe two airflows are combined is higher than at the outlet of thelow-pressure compressor, it is possible to provide a fan, an auxiliarycompressor, which imparts a higher pressure to the secondary airflow. Byway of example, this fan is an electrically driven fan.

Preferably a heat exchanger is provided which effects a heat transferbetween the exhaust gases in the exhaust-gas pipe system, on the onehand, and the secondary airflow, on the other hand, preferablydownstream of the first water injection means. In this way, it becomespossible for as much water as possible to be introduced into thesecondary airflow and to be evaporated using the heat from the exhaustgases.

It should be noted that, within the context of the description, whichfollows, and the claims, numerical words are used, such as first,second, third, etc. These numerical words are used only to identify theseparate components, and do not provide any indication of the number ofsimilar components which is or should be present in the installation.For example, it is conceivable to produce an installation in which thefourth heat exchanger, which is yet to be described, is absent, yet thefifth and sixth heat exchangers, which are yet to be described in moredetail, are nevertheless present.

Further advantageous embodiments of the installation according to theinvention are described in the claims and the following descriptionwhich is based on the drawing.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 shows a circuit diagram of an exemplary embodiment of theinstallation according to the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

FIG. 1 shows an installation for generating energy according to theinvention. This installation comprises a compressor assembly forcompressing air. In this example, the compressor assembly comprises:

a low-pressure compressor 1 with an air inlet 2 and an outlet 3,

a high-pressure compressor 4 with an inlet 5 and an outlet 6, the outlet3 of the low-pressure compressor being connected to the inlet 5 of thehigh-pressure compressor 4,

a compressor turbine assembly for driving the low-pressure compressor 1and the high-pressure compressor 4, which compressor turbine assemblyincludes a single compressor turbine 7, and which compressor turbineassembly has an inlet 8 and an outlet 9, the inlet 8 being connected tothe outlet of the high-pressure compressor 4.

In this example, the compressors 1, 4 and the compressor turbine 7 arearranged on a single common shaft 10.

A primary air path 12, extends between the outlet 3 and the inlet 5, viawhich primary air path 12 a primary airflow passes from the low-pressurecompressor 1 to the high-pressure compressor 4. An inlet end of asecondary air path 13 is connected to the said primary air path 12, insuch a manner that, of the compressed air originating from the outlet ofthe low-pressure compressor 1, a primary airflow passes to thehigh-pressure compressor 4 and a secondary airflow into the secondaryair path 13.

The airflow from the low-pressure compressor 1 is preferably divided insuch a manner that the primary airflow is greater than the secondaryairflow; by way of example, the primary airflow amounts to 85% and thesecondary airflow to 15% of the total airflow. The ratio between the twoairflows may be constant, for example by the secondary air path having adefined passage area with respect to the passage area of the primary airpath 12. If appropriate, control means can be provided, for examplevalve means, preferably in the secondary air path 13, foropening/closing and/or controlling the size of the passage area of thesecondary air path 13 with respect to the primary air path 12.

At the secondary air path 13, there are first water injection means 15for injecting water into the secondary airflow.

Fourth water injection means 17 are provided for cooling the primaryairflow in the primary air path 12.

As is generally known in connection with the injection of water, inwhatever way, it is desirable to cool the air and to increase the massflow rate in the installation, which offers various advantages.

In this example, a fan 18 is provided upstream of the first waterinjection means 15, at the secondary air path 13, for effecting alimited pressure increase in the secondary airflow. This fan 18 may havea low output and may, if appropriate, be electrically driven.

The installation shown in FIG. 1 also comprises a high-pressurecombustion device 20 upstream of the inlet 8 of the compressor turbine7. In this example, a low-pressure combustion device 25 is alsoprovided, in the shown example downstream of the outlet 9 of thecompressor turbine 7.

In the combustion devices 20, 25 each time a mixture of the compressedair (with the water vapour present therein) and of a suitable fuel isburnt.

The installation also comprises a power turbine 30, with a rotatableshaft 31 for releasing mechanical energy, for example for driving anelectric generator 32. The power turbine 30 has an inlet 33, which inthis case is connected to the outlet of the low-pressure combustiondevice 25, and an exhaust-gas outlet 35.

The installation also has an exhaust-gas pipe system, an inlet end 40 ofwhich is connected to the exhaust-gas outlet 35 of the power turbine 30.

In this example, an outlet end of the secondary air path 13 is connectedto the connection between the outlet 9 of the compressor turbine 7 andthe inlet of the low-pressure combustion device 25.

The exhaust-gas pipe system comprises a primary exhaust-gas path 41 anda secondary exhaust-gas path 42, which two paths 41, 42 are connected tothe outlet 35 of the power turbine 30, so that a primary exhaust-gasflow passes into the primary exhaust-gas path 41 and a secondaryexhaust-gas flow passes into the secondary exhaust-gas path 42.

The primary exhaust-gas flow is preferably greater than the secondaryexhaust-gas flow; by way of example, the ratio between the exhaust-gasflows is approximately the same as the ratio between the primary airflowand the secondary airflow as described above.

A first heat exchanger 50 effects a heat transfer between the exhaustgases in the exhaust-gas pipe system and the secondary airflow,preferably downstream of the first water injection means 15.

A second heat exchanger 60 effects heat transfer between the primaryexhaust-gas flow in the primary path 41, on the one hand, and theprimary airflow between the high-pressure compressor 4 and the inlet ofthe compressor turbine 7, on the other hand. In the specialist field,this second heat exchanger 60 is often referred to by the termrecuperator.

A third heat exchanger 70 effects a heat transfer between the exhaustgases in the secondary exhaust-gas path 42 and the secondary airflow inthe secondary air path 13 downstream of the first heat exchanger 50.

An outlet end of the secondary exhaust-gas path 42 is connected to theprimary air path 41 downstream of the second heat exchanger 60. Thefirst heat exchanger 50 is then arranged downstream of this connection,so that all the exhaust gases pass through the first heat exchanger 50.

A fourth heat exchanger 80 effects a heat transfer between the exhaustgases in the secondary exhaust-gas path 42 downstream of third heatexchanger 70, on the one hand, and the secondary airflow in thesecondary air path 13 downstream of the first heat exchanger 50, on theother hand.

The first heat exchanger 50 is preferably designed to extract as muchheat as possible from the exhaust gases before these exhaust gases areexpelled.

If appropriate, injected water can be recovered by injecting water inthe vicinity of the outlet of the exhaust-gas pipe system, which wateris collected together with the water, which was injected earlier.

In the variant illustrated, the outlet end of the secondary air path 13is connected to the connection between the compressor turbine 7 and thelow-pressure combustion device 25.

In a variant, a low-pressure combustion device is positioned in thesecondary air path 13 for burning a suitable mixture of the secondaryairflow and a fuel. This can be achieved, for example, by incorporatingthe combustion device 25 which is now illustrated in the secondary airpath 13, as indicated by dashed lines in FIG. 1, although obviouslyinstallations with a plurality of low-pressure combustion devices arealso conceivable.

Furthermore, a fifth heat exchanger 90 and a sixth heat exchanger 95 arealso provided in the installation shown, effecting a heat transferbetween the exhaust gases in the primary exhaust-gas path 41, on the onehand, and the primary airflow between the high-pressure compressor 4 andthe compressor turbine 7, on the other hand. In this case, as seen inthe direction of the primary airflow, the fifth and sixth heatexchangers are arranged upstream of the second heat exchanger 60.

It can also be seen that second water injection means 100 are providedfor the purpose of injecting water into the primary airflow between thefifth and sixth heat exchangers 90, 95.

Furthermore, the installation is provided with third water injectionmeans 110 for injecting water into the. Primary airflow between thehigh-pressure compressor 4 and the sixth heat exchanger 95.

In a variant, it is possible for there to be provided a plurality ofcompressor turbines instead of a single compressor turbine, for examplein such a manner that a compressor turbine drives the low-pressurecompressor and another compressor turbine drives the high-pressurecompressor.

In yet another variant, it is possible for a compressor turbine to drivean electric generator and for electric drive motors, which are coupledto the electric generator, to be provided for the purpose of driving oneor more compressors of the compressor assembly.

The injection of water into the secondary airflow and the supply of heatwhich has been extracted from the exhaust gases to the secondary airflowmay also take place in ways other than that shown in the figure. Forexample, it is possible for one or more heat exchangers to be arrangedupstream of the water injection means or for the water injection meansto be arranged at the same location as a heat exchanger, or for thewater injection means to be arranged between the heat exchangers.

As mentioned earlier, the water injection may take place in variousways, depending on the situation, for example in the form of a mist,steam.

The water which is to be injected may be preheated with the aid of heatwhich is extracted from the exhaust gases, but also with the aid ofwater which is extracted from the compressed air downstream of acompressor.

The cooling means for cooling the primary gas flow upstream of thehigh-pressure compressor may also be designed other than with waterinjection, for example with injection of cold air or another coolingmedium, or combinations of the various options. If appropriate, it ispossible for the air to be cooled at the inlet of the low-pressurecompressor or in the low-pressure compressor, for example if theinstallation is arranged in a hot environment.

The temperatures which may prevail in the installation as shown in FIG.1 are listed below by way of non-limiting example.

Air originating from low-pressure compressor 130° C.

Primary airflow after cooling by means of fourth water injection means40° C.

Primary airflow at high-pressure compressor outlet 165° C.

Primary airflow after cooling by means of third water injection means90° C.

Primary airflow downstream of recuperator 640° C.

Primary airflow at high-pressure combustion device outlet 850° C.

primary airflow at compressor turbine outlet 620° C.

Airflow at low pressure combustion device outlet 900° C.

Exhaust gas flow at power turbine outlet 640° C.

What is claimed is:
 1. An installation for generating energy,comprising: a compressor assembly for compressing air, comprising: alow-pressure compressor having an air inlet and an outlet, ahigh-pressure compressor having an inlet and an outlet, the outlet ofthe low-pressure compressor being connected to the inlet of thehigh-pressure compressor via a primary air path, a compressor turbineassembly for driving at least one-of the low-pressure compressor and thehigh-pressure compressor, the compressor turbine assembly having atleast one compressor turbine and an inlet and an outlet, the inletconnected to the outlet of the high-pressure compressor; cooling meansfor cooling the air at a location which lies upstream of the outlet ofthe high-pressure compressor; a combustion device for burning a suitablemixture of compressed air and a fuel; a power turbine with a rotatableshaft for delivering mechanical energy, the power turbine having aninlet connected to the outlet of the compressor turbine assembly, and anexhaust-gas outlet; an exhaust-gas pipe system, an inlet end of which isconnected to the exhaust-gas outlet of the power turbine; wherein asecondary air path is provided, which, at an inlet end thereof, isconnected between the outlet of the low-pressure compressor and theinlet of the high-pressure compressor, so that of the compressed airoriginating from the outlet of the low-pressure compressor, a primaryairflow passes via the primary air path to the high-pressure compressorand a secondary airflow passes into the secondary air path; a firstwater injection means provided at the secondary air path for injectingwater into the secondary airflow; and wherein an outlet end of thesecondary air path is connected to the connection between the outlet ofthe compressor turbine assembly and the inlet of the power turbine. 2.An installation according to claim 1, in which a fan is incorporated inthe secondary air path for increasing the pressure of the secondaryairflow.
 3. An installation according to claim 1, in which a first heatexchanger is provided, which effects a heat transfer between the exhaustgases in the exhaust-gas pipe system and the secondary airflow,preferably downstream of the first water injection means.
 4. Aninstallation according to claim 3, in which the exhaust-gas pipe systemcomprises a primary exhaust-gas path and a secondary exhaust-gas path,which are connected to the outlet of the power turbine, so that aprimary exhaust-gas flow passes into the primary exhaust-gas path and asecondary exhaust-gas flow passes into the secondary exhaust-gas path,in which a second heat exchanger is provided, which effects a heattransfer between the primary exhaust-gas flow, on the one hand, and theprimary airflow between the high-pressure compressor and the inlet ofthe compressor turbine assembly, on the other hand, and in which a thirdheat exchanger is provided, which effects a heat transfer between theexhaust-gases in the secondary exhaust-gas path and the secondaryairflow in the secondary air path.
 5. An installation according to claim3, in which the exhaust-gas pipe system comprises a primary exhaust-gaspath and a secondary exhaust-gas path, which are connected to the outletof the power turbine, so that a primary exhaust-gas flow passes into theprimary exhaust-gas path and a secondary exhaust-gas flow passes intothe secondary exhaust-gas path, in which a second heat exchanger isprovided, which effects a heat transfer between the primary exhaust-gasflow, on the one hand, and the primary airflow between the high-pressurecompressor and the inlet of the compressor turbine assembly, on theother hand, and in which a third heat exchanger is provided, whicheffects a heat transfer between the exhaust-gases in the secondaryexhaust-gas path and the secondary airflow in the secondary air path,and in which the secondary exhaust-gas path is connected, by means of anoutlet end, to the primary exhaust-gas path downstream of the secondheat exchanger, and in which the first heat exchanger is arrangeddownstream of this connection.
 6. An installation according to claim 3,in which the exhaust-gas pipe system comprises a primary exhaust-gaspath and a secondary exhaust-gas path, which are connected to the outletof the power turbine, so that a primary exhaust-gas flow passes into theprimary exhaust-gas path and a secondary exhaust-gas flow passes intothe secondary exhaust-gas path, in which a second heat exchanger isprovided, which effects a heat transfer between the primary exhaust-gasflow, on the one hand, and the primary airflow between the high-pressurecompressor and the inlet of the compressor turbine assembly, on theother hand, and in which a third heat exchanger is provided, whicheffects a heat transfer between the exhaust-gases in the secondaryexhaust-gas path and the secondary airflow in the secondary air path,and in which a fourth heat exchanger is provided, which effects a heattransfer between the exhaust gases in the secondary exhaust-gas pathdownstream of the third heat exchanger, on the one hand, and thesecondary airflow in the secondary air path downstream of the first heatexchanger, on the other hand.
 7. An installation according to claim 3,in which fifth water injection means are provided for the purpose ofinjecting water into the secondary airflow downstream of the first heatexchanger, for example between the third and fourth heat exchangers. 8.An installation according to claim 1, in which a low-pressure combustiondevice is positioned between the outlet of the compressor turbineassembly and the power turbine.
 9. An installation according to claim 8,in which the outlet end of the secondary air path is connected to theconnection between the compressor turbine assembly and the low-pressurecombustion device.
 10. An installation according to claim 1, in which alow-pressure combustion device is positioned in the secondary air pathfor the purpose of burning a suitable mixture of the secondary airflowand a fuel.
 11. An installation according to claim 1, in which a fifthand a sixth heat exchanger are provided, which effect a heat transferbetween the exhaust gases in the primary exhaust-gas path, on the onehand, and the primary airflow between the high-pressure compressor andthe compressor turbine assembly, on the other hand.
 12. An installationaccording to claim 11, in which second water injection means areprovided for the purpose of injecting water into the primary airflowbetween the fifth and sixth heat exchangers.
 13. An installationaccording to claim 1, in which third water injection means are providedfor the purpose of injecting water into the primary airflow downstreamof the high-pressure compressor.
 14. An installation according to claim1, in which the cooling means for cooling the primary airflow betweenthe outlet of the low-pressure compressor and the outlet of thehigh-pressure compressor are designed as fourth water injection means.15. An installation according to claim 1, in which a high-pressurecombustion device is positioned between the outlet of the high-pressurecompressor and the inlet of the compressor turbine assembly, for thepurpose of burning a suitable mixture comprising the compressed air anda fuel.
 16. An installation according to claim 1, in which thecompressor turbine assembly includes a single compressor turbine, whichis arranged on a common shaft with the low-pressure compressor and thehigh-pressure compressor.
 17. An installation according to claims 1, inwhich a compressor turbine drives an electric generator, and in whichelectric drive motors, which are coupled to the electric generator, areprovided for the purpose of driving one or more compressors of thecompressor assembly.
 18. An installation according to claim 1, whereinthe compressor turbine assembly comprises a plurality of compressorturbines arranged in series.